Friday, March 21, 2014

A recent protest by organic activists outside a Chicago Home Depot highlighted something of the current debate over pesticides and bees. It also reminded me that no one wants to go on record as being "against the bees". Check out the video above.

The folks in the bee costumes in the above video are protesting the retail sale of "bee-killing" insecticides called neonicotinoids. They represent groups demanding that these insecticides not be sold, and that stores begin selling only nursery plants that have not been treated with these insecticides. I've blogged about this issue in the past, and reported on some recent urban incidents that could affect the pest control industry.

Over the past few days there has been some interesting discussion on this subject in a chat group that I belong to. I thought I would share some of the more interesting comments and new studies on the subject.

Bee experts are mostly in agreement that Colony Collapse Disorder (CCD) in honey bees is not as simple as "bad" pesticides. In fact pesticides may have little to do with bee declines in some areas. Australia may be instructive in this regard. Australia uses neonicotinoid insecticides like the rest of the world, but Australian honey bees are not in decline. A new Australian government report out this month confirms as much, and concludes that take as a whole, neonicotinoid use has led to an "overall reduction in the risks to the agricultural environment from the application of insecticides."

A recent collaborative paper in the journal mBio, by Chinese and U.S. scientists, found a virus that has been known for many years, tobacco ringspot virus (TRSV), that is infecting honey bees. This virus is the first known plant virus that has mutated and adapted into an animal-infesting virus. It appears to be transmitted to bees via pollen, and also by varroa mite. And its presence in bee colonies appears to be associated with gradual declines in bee colony vitality.

In fact, varroa mites in combination with viruses are currently under close scrutiny as a major explanation for CCD. According to Dr. Richard Cowles, with the Connecticut Agricultural Experiment Station, "When combined with work on Israeli Acute Paralysis Virus and a demonstration that irradiation of hive equipment from CCD could prevent nukes from succumbing to CCD, the strongest evidence for the cause of CCD is the varroa/viral combination." An interesting side observation is that Australia does not yet have varroa mite, which lends strength to the argument for a mite-vectored virus explanation for the disease.

Most studies that have found neonicotinoids in pollen have been on herbaceous plants. In one study on red maple trees, a dissertation by Dr. Josephine Johnson at the University of Maryland, no imidacloprid was found in tree nectar and only extremely low levels in pollen (bees feeding on these trees had no evidence of insecticides, nor in hive collected nectar). So if you do neonicotinoid root applications on trees per label instructions, there is no evidence right now that such applications pose any risk to pollinators.

Two new Washington State University Extension publications are now available on CCD and neonicotinoids. The first publication by Lawrence and Sheppard, provides an overview of the problem with an explanation of the various factors thought to contribute to CCD. How to Reduce Bee Poisoning from Pesticides is a thorough overview of practical ways to reduce the risk of bee poisoning due to pesticides, and includes a table of most commonly used pesticides with their potential risks to bees.

None of this is to say that there are no legitimate concerns about the toxicity of neonicotinoids to pollinators. These products are certainly toxic to bees, and at levels lower than previously recognized. But research in this area is ongoing, and our understanding of the possible factors that might be hurting bee populations is much better than it was a few years ago. Despite what you might hear, both EPA and the pesticide industry is taking pollinator concerns seriously and is acting to make sure that you have safe tools to control pests effectively. After all, who wants to be "against the bees"?

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About Me

I have served as entomology specialist for Texas AgriLife Extension since 1989. I get to work with, and for, a bunch of great people including pest management professionals, school facilities managers, extension volunteers, researchers and other extension professionals. My areas of specialty center on research on insects affecting man including spiders, scorpions, fire ants, termites and others. My program also focuses on training school maintenance professionals in principles of integrated pest management (IPM). Our goal is to make schools healthier, cleaner places to study and live.